A method for preparing D-valine from L-valine by racemization and chemical resolution is presented. The resolving reagent, D-2,3-dibenzoyl tartaric acid was obtained by hydrolyzation of D-2,3-dibenzoyl tartaric anhydr...A method for preparing D-valine from L-valine by racemization and chemical resolution is presented. The resolving reagent, D-2,3-dibenzoyl tartaric acid was obtained by hydrolyzation of D-2,3-dibenzoyl tartaric anhydride prepared by reaction of benzoyl chloride with D-tartaric acid. DL-valine was prepared by racemization of L-valine in the presence of aldehyde in a medium of acetic acid at 100 to 110°C for 3 h. In the presence of mineral acid, reaction of D-2,3-dibenzoyl tartaric acid with DL-valine formed diastreroisomeric salts at 84 to 95°C. Salt composed of D-2,3-dibenzoyl tartaric acid and D-valine precipitated when the diastreroisomeric salts mixtures were cooled to 15°C. The salt was reacted with base giving D-valine with yield of 70% to 80% and optical purity of over 98%.展开更多
The electrochemical behavior of N,N-diethyl-p-nitroso aniline was carried out using SWV （square wave voltammetric） at HMDE. A well defined reduction peak was observed at （-0.214） volt versus the reference electro...The electrochemical behavior of N,N-diethyl-p-nitroso aniline was carried out using SWV （square wave voltammetric） at HMDE. A well defined reduction peak was observed at （-0.214） volt versus the reference electrode （Ag/AgC1/sat. KCI）, calibration curve was constructed in phosphate buffer （pH = 7.0）, the relationship is linear within the concentration range 1.283 × 10.5 M - 3.66 × 10.5 M with the correlation （R = 0.9923）. The serial addition ofCPM （chlorpheniramine maleate） leads to the decrease in the reduction current peak （Ip）, quantitatively, the plot of Alp （Ip - Ip） where, Ip： Peak current of N, N-diethyl-p-nitroso aniline alone, lp： peak current of N,N-diethyl-p-nitroso aniline in the presence of CPM, versus concentration is linear within the concentration range 0.984 × 10-6 M - 9.756 × 10-6 M, the correlation coefficient was 0.9954. The method was successfully applied to determine CPM in different types of pharmaceutical formulations, and compared with standard method from British Pharmacopeia [1].展开更多
文摘A method for preparing D-valine from L-valine by racemization and chemical resolution is presented. The resolving reagent, D-2,3-dibenzoyl tartaric acid was obtained by hydrolyzation of D-2,3-dibenzoyl tartaric anhydride prepared by reaction of benzoyl chloride with D-tartaric acid. DL-valine was prepared by racemization of L-valine in the presence of aldehyde in a medium of acetic acid at 100 to 110°C for 3 h. In the presence of mineral acid, reaction of D-2,3-dibenzoyl tartaric acid with DL-valine formed diastreroisomeric salts at 84 to 95°C. Salt composed of D-2,3-dibenzoyl tartaric acid and D-valine precipitated when the diastreroisomeric salts mixtures were cooled to 15°C. The salt was reacted with base giving D-valine with yield of 70% to 80% and optical purity of over 98%.
文摘The electrochemical behavior of N,N-diethyl-p-nitroso aniline was carried out using SWV （square wave voltammetric） at HMDE. A well defined reduction peak was observed at （-0.214） volt versus the reference electrode （Ag/AgC1/sat. KCI）, calibration curve was constructed in phosphate buffer （pH = 7.0）, the relationship is linear within the concentration range 1.283 × 10.5 M - 3.66 × 10.5 M with the correlation （R = 0.9923）. The serial addition ofCPM （chlorpheniramine maleate） leads to the decrease in the reduction current peak （Ip）, quantitatively, the plot of Alp （Ip - Ip） where, Ip： Peak current of N, N-diethyl-p-nitroso aniline alone, lp： peak current of N,N-diethyl-p-nitroso aniline in the presence of CPM, versus concentration is linear within the concentration range 0.984 × 10-6 M - 9.756 × 10-6 M, the correlation coefficient was 0.9954. The method was successfully applied to determine CPM in different types of pharmaceutical formulations, and compared with standard method from British Pharmacopeia [1].
